Activating transcription factor 3 is downregulated in hepatocellular carcinoma and functions as a tumor suppressor by regulating cyclin D1

Objective: To investigate the expression as well as biological roles of activating transcription factor 3 (ATF3) in human hepatocellular carcinoma (HCC) cells. Methods: Real time PCR and western blot were applied to detect the expression of ATF3 in human HCC specimens. MTT assay was used to analyze cell proliferation after ATF3 was overexpressed. The expression of cyclin D1 was detected by real time PCR in ATF3-silenced/-overexpressed cells and HCC samples. Correlation coefficient was finally analyzed between ATF3 and cyclin D1 in the HCC samples. Results: The expression of ATF3 was found to be downregulated in tested HCC specimens. Cellular MTT assays showed that cell proliferation was suppressed in ATF3-overexpressing HepG2 cells. In addition, cyclin D1 gene expression exhibited negative correlation with ATF3 in both cell lines and tissue samples. Conclusion: Low expression of ATF3 may function as a tumor suppressor via inhibiting cyclin D1 in HCC.